This invention relates to fuel fill systems in motor vehicles. More particularly, this invention relates to fuel fill systems having fuel vapor recirculation features.
Fuel fill systems are found in motor vehicles such as automobiles, trucks, boats, airplanes, and the like, and serve to transfer fuel provided by a source external to the vehicle (e.g., a gas pump) to a fuel storage tank located in the vehicle. In general, fuel fill systems include a funnel assembly, called a fuel filler neck, connected to the fuel storage tank by one or more lengths of tube. The fuel filler neck receives fuel delivered from the external fuel source, and the one or more lengths of tube deliver the fuel to the fuel storage tank. A removable cap (e.g., a gas cap) is secured to the fuel filler neck to seal the fuel fill system after the fueling process.
Environmental regulations imposed on the automotive industry and on the fuel delivery industries severely limit the amount of fuel vapor that can permeate from the fuel fill system of motor vehicles. To help meet and exceed these regulations, various improvements in technology have been developed. For example, various types of vapor permeation resistant tubing have been proposed to limit the amount of fuel vapor that can permeate from the system through the tubing. Examples of such tubing are provided in U.S. Pat. No. 6,591,871, entitled “Low Permeation Polybutylene Terephthalate and Polybutylene Napthalate Fuel and Vapor Tubes”; and in U.S. Pat. No. 6,293,312, entitled “Thermoplastic Tubing”.
In addition to advancements in the materials used in fuel fill systems, advancements have been made in the design of fuel fill systems. One example of an advancement in the design of fuel fill systems is found in so-called Onboard Refueling Vapor Recovery (ORVR) equipped fuel fill systems. ORVR equipped fuel fill systems include a vapor recirculation tube, which provides a separate fluid path between the fuel storage tank and the fuel filler neck. The recirculation tube provides a path for receiving the air and fuel vapor mixture (referred to hereinafter as “fuel vapor”) displaced from the fuel storage tank during fueling, and reintroduces the displaced fuel vapor to the fuel filler neck. The flow of the fuel vapor in the vapor recirculation tube may be controlled by one or more valves, and may be filtered by one or more filters.
While innovations such as vapor permeation resistant tubing and ORVR equipped systems significantly reduce the amount of fuel vapor that is allowed to escape from a fuel fill system, further reductions are desired.